Lectins: Getting Familiar with Translators of the Sugar Code

Abstract

The view on the significance of the presence of glycans in glycoconjugates is undergoing a paradigmatic change. Initially mostly considered to be rather inert and passive, the concept of the sugar code identifies glycans as highly versatile platform to store information. Their chemical properties endow carbohydrates to form oligomers with unsurpassed structural variability. Owing to their capacity to engage in hydrogen (and coordination) bonding and C-H/π-interactions these “code words” can be “read” (in Latin, legere) by specific receptors. A distinct class of carbohydrate-binding proteins are the lectins. More than a dozen protein folds have developed carbohydrate-binding capacity in vertebrates. Taking galectins as an example, distinct expression patterns are traced. The availability of labeled endogenous lectins facilitates monitoring of tissue reactivity, extending the scope of lectin histochemistry beyond that which traditionally involved plant lectins. Presentation of glycan and its cognate lectin can be orchestrated, making a glycan-based effector pathway in growth control of tumor and activated T cells possible. In order to unravel the structural basis of lectin specificity for particular glycoconjugates mimetics of branched glycans and programmable models of cell surfaces are being developed by strategic combination of lectin research with synthetic and supramolecular chemistry.

Entomotoxic and nematotoxic lectins and protease inhibitors from fungal fruiting bodies

“…Binding of the carbohydrate is usually achieved by multiple weak interactions that result in high specificity, avidity, and/or affinity of the lectin for the carbohydrate ligand (Andre et al 2015). Lectins were first classified according to their carbohydrate-binding specificity and, later, according to their sequence homology and evolutionary relatedness.…”

Unraveling functional significance of natural variations of a human galectin by glycodendrimersomes with programmable glycan surface

“…Taking advantage of the capacity of carbohydrates to store biological information, glycans are a versatile means to generate the required cell-surface recognition (1)(2)(3). These molecular signals are docking sites for tissue receptors (lectins), which translate the glycan-based information into adhesion and bridging, often triggering outside-in signaling (3)(4)(5)(6). Key insights into these processes have been obtained by teaming up synthetic chemistry, which delivers a defined custom-made matrix, with bioassays using cells (2,7,8).…”

Galectin-related protein: An integral member of the network of chicken galectins

“…In full agreement to the data from Western blotting, C-GRP positivity was present in sections of bursa but no other tissue, when testing 4-week-old animals. Obtaining the known regional selectivity for canonical CGs, as documented for example in sections of kidney previously [7,38], ensured the reliability of the technical procedure. These immunohistochemical series thus solidified the focus on this tissue type.…”